Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
1104 AM EST Sat Mar 09 2019
Valid 12Z Tue Mar 12 2019 - 12Z Sat Mar 16 2019
...Heavy Snow/Wind Threat for the North-Central U.S. Wednesday and
Thursday...
...Heavy Rain/Strong Thunderstorm Threat from the South-Central
Plains/MS Valley to the Mid-South/Southeast Tuesday to Friday...
...Overview...
It seems that the last in a series of potent storm systems in this
active flow pattern will trek out of the Southwest/Four Corners
region Tuesday and lift northeastward toward the Upper
Midwest/Great Lakes by Thursday. This will spread a large area of
potentially heavy rain/severe convection and runoff threat from
the central/southern Plains through the Mid-South/Southeast as
marginally cold air to the north supports a heavy snow/wind threat
for the north-central Rockies/Plains and Upper Midwest. By next
weekend, the pattern appears much quieter with high pressure
forecast to dominate the western/central parts of the lower 48.
...Guidance and Uncertainty Assessment...
Recent guidance has been inconsistent run to run with the timing
of driving mid-upper level trough energy/height falls. However,
guidance has been quite consistent showing ultimate development of
yet another major storm to traverse the Southwest leading into
powerful storm genesis over the central U.S. A concensus of latest
guidance offers a solution in line with WPC continuity.
...Weather Highlights and Hazards...
Main system of interest in the medium range will lift out of the
Southwest and deepen quite smartly into southeastern Colorado by
Wednesday morning. Precipitation will expand in coverage out of
Arizona and New Mexico eastward, focused on the central/southern
Plains (northern Texas northward) Tue/Wed. To the east, a front
across the Gulf will lift northward as a warm front and bring
widespread rainfall and embedded convection into the
Mississippi/Tennessee Valley Wednesday then into
Alabama/Georgia/southern Appalachians Thursday. The potential for
several inches of rain exists over a large area that will be
further refined over the next several days, but atmospheric and
ensemble signals continue to be strong. To the north, cold enough
air will support snow on the northwest/north side of the surface
low that will occur with strong winds (i.e., possible blizzard
conditions). A cold rain (perhaps over an inch to an inch and a
half) will fall to the southeast of the surface low over some
areas that will receive significant snow in the short term (e.g.,
southern Minnesota). The surface low will depart through southern
Canada Friday as colder air is dragged in behind it across the
Great Lakes, enhancing lake-effect snows.
Temperatures will remain below average in the west but perhaps
moderate just a bit by next weekend. In the east, post-front
airmass Tuesday will be chilly (below average by a few degrees)
but then warm up ahead of the central states' system by Thursday
into Friday.
Fracasso/Schichtel
Additional 3-7 Day Hazards information can be found on the WPC
medium range hazards chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php
WPC medium range 500mb heights, surface systems, weather grids,
quantitative precipitation, winter weather outlook probabilities
and heat indices are at:
https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif
https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html
https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml
https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4
https://www.wpc.ncep.noaa.gov/heat_index.shtml